Explain why the viscosity of multigrade motor oils is less temperature-dependent than that of single-grade motor oils.

Video transcript

Hey everyone in this example were asked why the viscosity of liquid polymers, long molecules made up of repeating structural units like polyethylene, glycol have or are less temperature dependent than that of water. So what we should recall is that at high temperatures, polymers unwind and become chains. Whereas at low temperatures our polymers quayle up and so because they quail up at lower temperatures, we would say that therefore we have weaker inter molecular forces contributing less to the viscosity. In comparison to higher inter molecular forces associated with the chain form of polymers, which as we stated above, only occurs when the temperature is highest or higher. We want to recall that water is a small molecule. It's not going to be a polymer because we just have two Atoms of hydrogen bonded to oxygen. And because this is such a small molecule, the viscosity of water is not going to be affected by the shape of our molecule. Like that is true for polymers. So we can say overall polymers for our final answer, polymers change shape depending on temperatures, thus the viscosity is affected. And so this explanation here will be our final answer to complete this example. So I hope that everything I reviewed was clear. If you have any questions, please lead them down below and I will see everyone in the next practice video